Liquid laundry detergent products offer a number of advantages over dry, powdered or particulate laundry detergent products. Liquid laundry detergent products are readily measurable, speedily dissolved in wash water, non-dusting, are capable of being easily applied in concentrated solutions or dispersions to soiled areas on garments to be laundered and usually occupy less storage space than granular products. Because liquid laundry detergents are usually considered to be more convenient to use than granular laundry detergents, they have found substantial favor with consumers.
However, while liquid laundry detergents have a number of advantages over granular laundry detergent products, there are also disadvantages entailed in using them. In particular, laundry detergent composition components which may be compatible with each other in granular products may tend to interact or react with each other in a liquid, and especially in an aqueous liquid environment. Components such as peroxygen bleaches and bleach precursors can be especially difficult to incorporate into liquid laundry detergent products with an acceptable degree of compositional stability. Poor compositional stability may cause some active ingredients to react with each other prematurely in the product, which can cause physical instabilities such as phase splitting, sedimentation and solidification. This premature reaction may also cause chemical instabilities which can lead to product discoloration or color change, oxygen gas liberation, oxidation of sensitive ingredients (especially enzymes) and, eventually, detersive performance loss.
One approach for enhancing the chemical compatibility and stability of liquid laundry detergent products has been to formulate substantially anhydrous, non-aqueous liquid laundry detergent compositions. Generally, the chemical stability of the components of a non-aqueous liquid laundry detergent composition increases as the amount of water in the laundry detergent composition decreases. Moreover, by minimizing the amount of water in a liquid laundry detergent composition, one can maximize the surfactant activity of the composition. Non-aqueous liquid laundry detergent compositions have been disclosed in Hepworth et al., U.S. Pat. No. 4,615,820, Issued Oct. 17, 1986; Schultz et al., U.S. Pat. No. 4,929,380, Issued May 29, 1990; Schultz et al., U.S. Pat. No. 5,008,031, Issued Apr. 16, 1991; Elder et al., EP-A-030,096, Published Jun. 10, 1981; Hall et al., WO 92/09678, Published Jun. 11, 1992 and Sanderson et al., EP-A-565,017, Published Oct. 13, 1993. See also U.S. Pat. No. 4,889,652, issued Dec. 26, 1989 to Sullivan et al.; U.S. Pat. No. 5,176,173, issued Jan. 5, 1993, to Dixit et al.; U.S. Pat. No. 4,828,723, issued May 9, 1989, to Cao et al. and U.S. Pat. No. 5,589,370, issued Dec. 31, 1996, to Ratuiste et al. for the use of microspheres in detergent compositions.
Fully-formulated detergents typically comprise detersive surfactants, builders and alkalinity sources. However, certain common detergent ingredients such as builders and alkalinity sources are not generally soluble in most non-aqueous solvents. Because these ingredients are typically denser than the liquid matrix of a non-aqueous detergent composition, they have a tendency to separate out of liquid detergent products and form sediments on the bottom of the detergent container between their date of manufacture and their usage by the consumer. This segregation can, in turn, have an adverse effect on product aesthetics, usage instructions, pourability, dispensability, stability and particularly on overall cleaning effectiveness.
Given the foregoing, there is a continuing need to formulate non-aqueous liquid laundry detergent compositions comprising ingredients (e.g. builders, alkalinity sources) which are insoluble in the non-aqueous detergent liquid without the undesirable separation and sedimentation phenomena discussed above. Accordingly, it is a object of the present invention to provide non-aqueous liquid laundry detergent compositions which have excellent cleaning and detersive performance without displaying deleterious separation and segregation phenomena. This is achieved by the present process which converts such high density detergent ingredients into a lower density form which can be stably suspended in a non-aqueous liquid detergent matrix.